One of those things where you just put money into it and wait, provided you think useful things can be built atop it. In the case of citycoins in general, passive income is built into the assets, albeit at a declining rate to due gradual supply increases.
That said, there are of course people who trade these things, but short of being able to manipulate markets (trading bots pushing demand up and down on the one exchange these assets are listed on, hence the aforementioned "major liquidity issues"), I don't see much promise in active investment here.